If you use a ‘junk drawer’ group in DEVONthink, the more you add to it the worse the automatic and semi-automatic classification becomes. This happens because DEVONthink looks at all your groups to find out where the selected documents fit into. And with a well filled junk drawer group, everything always fits in there. But you can simply take any group out of the classification by selecting it, opening the Info panel (Tools > Show Info…, Command-Shift-I), and checking ‘Exclude from classification’. Exclude your junk drawers from classification and give DEVONthink’s AI an intelligence boost.